■Lecturer: Dr. Windi Muziasari Researcher in the University of Helsinki, and CEO of Resistomap Co.

■Abstract: Antibiotic resistance has become a serious threat to the efficacy of antibiotics used in human and veterinary medicine. Abundance and prevalence of antibiotic resistance genes (ARGs) in the environmental is important for predicting a risk of the ARGs.

The two main topics of the talk are (1) determining the abundance and diversity of ARGs and mobile genetic elements in sediments impacted by fish farming and (2) investigating the major source of ARGs in the farm sediments in the Northern Baltic Sea. Correlations between ARGs and mobile genetic elements were also examined. This study employed a high-throughput SmartChip qPCR, which permits quantifying up to 384 ARGs and mobile elements.

Fish farming impacts the composition of ARGs in sediments below fish farms in the Northern Baltic Sea. However, the impact is local and mostly limited to enrichment of ARGs associated with antibiotics used at the farms. The risk of ARG spread from the farm sediments to the surrounding sediments is low at this moment. However, the enriched ARGs persist in the farm sediments during the 6-year even when the selection pressure is negligible. Moreover, significant correlations between mobile elements and ARGs may imply the persistence of certain ARGs in the fish farming environments and their potential for mobilizing the ARGs to other bacteria including pathogens. The persistence of ARGs at the farm reduces the efficacy of the antibiotics against fish diseases. Certain ARGs might be constantly introduced by feces of the fish into the sediments below the fish farms.

Our SmartChip qPCR is a powerful tool to provides unprecedented insights into the ARG composition in the environmental resistome associated with fish farming.